BMA400 datasheet(21/121 Pages) BOSCH

21 / 121 page

Bosch Sensortec | BMA400 Data sheet

21 | 121

Modifications reserved | Data subject to change without notice

Document number: BST-BMA400-DS000-13 Revision_2.2_012025

Wake-up interrupt on activity

In low-power mode BMA400 wake-up interrupt is triggered, if the conditions as defined by the

configuration registers are fulfilled. This function is always on in low power mode, and can be mapped

to interrupt pin. The wake-up can be used for auto wake-up of BMA400 to normal mode and/or the

wake-up of the external MCU by mapping the interrupt to the interrupt pin.

The wake-up interrupt function evaluates acceleration data and is set as soon as the value of the

sampled data exceeds the preconfigured acceleration threshold. The comparison of the current

acceleration value with a reference is configurable between relative reference (last sampled value

stored in the register) and absolute reference (the reference values are set once and not changing

after each acceleration conversion). The delay between two data conversions is 40ms (25Hz

conversion ODR in Low-power).

The auto wake-up by wakeup interrupt on activity is activated by setting AUTOWAKEUP_1.wkup_int

bit. The wakeup status is available in INT_STAT0.wkup_int.

When woken up, an interrupt can be generated and mapped to the interrupt pins.

The wake-up interrupt function supports following configurations:

•

Selectable axis for wake-up: the wake-up interrupt function supports independent

activation/deactivation of each acceleration axis for function evaluation. This is performed by

setting the bits WKUP_INT_CONGIF0.wkup_X/Y/Z_en accordingly.

•

Reference update mode (configured by setting WKUP_INT_CONFIG0.wkup_refu)

wkup_refu<1:0>

description of wake-up interrupt references update mode

b00

manual update

The references (int_wkup_refX/Y/Z) are not updated automatically, they shall be set manually by user

in low-power mode.

b01

one time

The references is updated every time at entering low power mode. The first measured acceleration in

Low-power mode is used as reference.

b10 or b11

every time

The reference is updated every time after the acceleration conversion in low-power mode

The reference values are 8-bit signed values. The activity measurement takes the upper 8

bits of the acceleration value and compares against the reference

WKUP_INT_CONFIG[2-4].int_wkup_ref[x,y,z].

•

Threshold for activity detection: the threshold for activity detection (comparison of the difference

between the measured acceleration data and reference acceleration data) has 8-bit resolution,

corresponding to the upper 8 bits of the absolute value of the 12bit acceleration,

WKUP_INT_CONFIG1.int_wkup_thres.

•

Number of samples for decision: the number of samples for wake-up decision is configured

between 1 and 8 by the register WKUP_INT_CONFIG0. num_of_samples (number of samples

is the register value + 1).

BMA400 Datasheet(PDF) 21 Page - Bosch Sensortec GmbH

BMA400 Datasheet(HTML) 21 Page - Bosch Sensortec GmbH

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL